Dockside

Radio Control Boat Modeler, Dec 2001

LETTERS FROM OUR READERS

Do-it-yourself Repairs

I have a problem. My new 29-inch fiberglass boat was damaged in a race, and I was wondering if you know someone who could repair it and paint it for me. I really enjoy your RC boat mag. Thanks.

ALAN BANKHEAD

Alan, it's easier than you think to repair a hull. Sending a boat to someone to have it repaired may seem simple, but it is often very expensive because you must pay for that person's time and effort. In the August 2001 issue, we published an article by Jerry Dunlap on how to repair race damage to fiberglass and plastic hulls. Give it a try; you'll save lots of money. GY

Legal Mods

Good magazine and articles. In reference to Jerry Dunlap's article about the modifications to the drive cable in the 7.5 K&B outboard engine (October 2001 issue), is this cable mod legal to run under NAMBA rules? Also, don't you think it makes a difference how the drive cable is installed? Since the cable is wound, it will shorten when spun in one direction and will lengthen when spun in the opposite direction. This is why you need to install a flex cable with a 1/32-inch space between the tail shaft and the strut.

Keep up the good work. [email]

JAY RANDOLPH

Lilac City Model Boat Club

Jay, the use of metal shaft tubes is legal in NAMBA stock classes, and you are probably correct about cable flexing (lengthening and shortening), but I don't think it flexes enough to make any difference.

I've installed cables both ways for years without binding. This doesn't mean it's right; it's just what I've been doing. Good luck with your NAMBA racing. JERRY DUNLAP

Dyno Interest

I just read Mike Hoffmeister's article on the QD25 gas engine and would like to learn more about the dynamometer he used to test it. Is the device available commercially? In addition to building RC sailboats and a steam launch, I build experimental internal combustion engines and am looking for a way to test them in my shop. Thanks for your help.

DAVE BOWES

Dave, I built our dyno from scratch, but I had some help with the data logger and software. I do not offer the dyno for sale, but all of the info I used to design it came from www1.cedar-rapids.net/tdkmotor/; also, there is still some info on my old website:

http://home.sprintmail.com /~mikejhoff/dyno.htm.

Please have a look; with any luck, you will come away with enough good ideas to get started building your own dyno! If you have specific questions, please let me know.

MIKE HOFFMEISTER

Happy Experimenter

My name is Pablo, and I live in Jacksonville, FL. For my first model, I am slowly building a nitro-powered catamaran so I can learn more about model boating as I go along. And I really enjoy the camaraderie and excitement at racing events.

I own a .61 O.S. Max marine engine that is very nice for a 48-inch-long catamaran. However, I have a question. I need to know if there is a backup system I can implement on the catamaran in case the engine stalls out in the middle of the lake. I don't care if it makes the boat heavier or more sophisticated. I have seen an RC boat that has a glow-- powered engine with an electric motor as a backup in case the engine stalls. The electric motor is coupled via a clutch to the main drive shaft. I love that setup but have been unable to find a store that sells it or a website that even has information about it. Another system I like has a switch that's linked to the throttle; if the throttle is pulled back far enough, the switch activates power from a 1.5V battery directly to the glow plug. Any suggestions or information you may have would be great. I enjoy your magazine very much; you and your colleagues do a remarkable job. [email]

PABLO

Pablo, tinkering is the glue that holds our hobby together, and many of the things we now take for granted were devised by experimenters like you. The boat you refer to that has the electric backup motor is the Traxxas Nitro Vee with the "Return-to-Shore" electric-motor feature. It works very well and is a popular glow-powered boat. The unit that energizes the engine's glow plug when the throttle is retarded is known as an onboard glow driver. These are available from many manufacturers and greatly increase the engine's ability to idle reliably.

If you want to install an electric starter on your engine, the most popular one is the Fema drive unit available from Hobby Lobby Intl. Give them a call at (615) 373-1444 and tell them which engine you have. Have fun! GY

Write to US. We welcome your comments and suggestions. Letters should be addressed to "Dockside," Radio Control Boat Modeler, 100 East Ridge, Ridgefield, CT 06877-4606 USA, or send an email to rcboatmodeler@airage.com. Letters may be edited for clarity and brevity, and they must include an address or telephone number so we can verify the sender's identity. We regret that owing to the tremendous number of letters we receive, we can't respond to every one.